low brightness

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Permalink Reply by Scott Davidson on May 11, 2011 at 4:32pm

I work with this two ways. 

 

1) Using the Image adjustment controls help a lot:  http://nxt.flamingo3d.com/page/image-adjustment. The Burn contol is the trick here.

 

2) I also put the lights on separate channels.  This allows me to increase the strength of the HDRI after rendering using the lights.

 

3) Some HDRI images are set to very low lighting values.  So to get more range using channels, I might set the Intensity of the HDRI to 20. 

 

Using these tricks does it help?

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Permalink Reply by eggy on May 11, 2011 at 4:51pm

thanks for your quick reply.   I will try.   I do a lot of photoshop, in the photoshop world burning things out is bad because you loose image dynamic range, I have tried burn in NXT and applying too much "blows" out the dynamic range (you loose details in the lighter tones).  

 

Anyway I like your idea of putting the lights on diff. channels, will have to research this to figure out how to do it.

 

HDRIs are low brightness, would have never thought that, glad I asked, also never would have thought to go to 20 since most controls in Rhino and NXT seem more sensitive.    

 

How do I get more diffuse shadows around the legs of this item?  Is it a function of letting NXT run longer?

Attachments:

• sharp shadows.JPG, 7 KB

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Permalink Reply by Patris on May 11, 2011 at 11:01pm

If you use a lot of photoshop then try creating two or three single images from one finished rendering using light channels and adjustments with nxt, and then you can combine them as layers in photoshop, work with mask or eraser ,and merge them to one image.  I get good results using this method. It helps me to put light where i have too dark spots.

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Permalink Reply by Scott Davidson on May 12, 2011 at 8:39am

Another option also is to save the image as an NXT image format.  This retains the lighting values, channels and alpha channels.  Then,using the NXT Image editor (stand alone program, 32-bit luminence format), you can continue to adjust exposure and change the lighting channel values.  For the image editor you can save a bitmap or an hdri image.

 

I have not tried it, but you could also save an HDR image out of Flamingo, then open that in the newer versions of Photoshop and work on it in luminance 32-bit color space.  It would give you a broader range.

 

A thrid way I have done this is save a HDR file out of Flamingo and take it into a HDR editing program.  There are a lot you can do with adaptive image adjustment.  I have used:

 

http://www.hdrsoft.com/ 

or

http://www.fhotoroom.com/products/artizen/artizen.asp

 

 

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Permalink Reply by Scott Davidson on May 12, 2011 at 8:43am

The sharp shadows are typical artifacts for the default renderer.  Early passes will show many sharp shadows, especially on grey groundplanes.  As more passes complete, the shadows will soften and combine.  So let the image cook longer.

 

Another option in this case is turn on the Pathtracer. Because it uses a different rendering engine it will nto create the sharp shadows as an artifact.  It will start out very noisy and refien over time.  Fr product images I am using the pathtracer more and more. 

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Permalink Reply by eggy on May 12, 2011 at 9:51am

is pathtracer slower?  seems so.  get a very grainy, image made of dots after more than 10 minutes

on a 1500000 pixel render.  is this normal

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Permalink Reply by Scott Davidson on May 12, 2011 at 11:50am

It really depends from rendering to rendering.  But, no I am not surprised. Sometimes the Pathtracer is faster to get to the results you want, sometimes it is default. 

 

I normally will render at much lower resolutions for testing, then using the farm, send off a much larger image and let it render in the background.

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